Compressor waste heat recovery system

Abstract

A compressor waste heat recovery system belongs to the technical field of coal gasification production. The system is connected with a steam turbine, a low-pressure cylinder, a high-pressure cylinder and a process gas pipeline through a shaft, a first-section impeller and a second-section impeller are arranged in the low-pressure cylinder, and a third-section impeller and a fourth-section impeller are arranged in the high-pressure cylinder; a process pipeline is sequentially connected with a first-section inlet separator, a first-section impeller, a first-section outlet cooler and a first-section outlet separator and then connected with a second-section impeller, a high-pressure CO2 recuperator, a second-section outlet cooler, a high-pressure CO2 recuperator, a second-section outlet cooler and a second-section outlet separator. And then the gas is connected to a third-section impeller, a third-section outlet cooler, a third-section impeller outlet separator, a fourth-section impeller and a high-pressure CO2 recuperator, and then is connected with a pass outlet pipe. The system solves the problems of poor pulverized coal fluidity, frequent pulverized coal bin bridging and large coal line fluctuation caused by low high-pressure CO2 temperature of the coal gasification device, and meanwhile, the thermal load of a water cooler at a second-section outlet of a low-pressure cylinder of a compressor and the steam consumption of a high-pressure CO2 heater of the coal gasification device are reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of coal gasification production, and in particular relates to a compressor waste heat recovery system. Background Art

[0002] In the device that produces methanol by using pulverized coal pressurized gasification technology, the coal gasification device needs to use high-pressure inert gas. High-pressure N2 is used in the initial start-up of the device. After the device is started to the CO2 desorption tower in the low-temperature methanol washing process to produce CO2, it is pressurized by the compressor and sent to the coal gasification device to replace high-pressure N2. The temperature of the high-pressure CO2 gas at the outlet of the CO2 compressor is about 90°C. In actual production, due to the low temperature, the fluidity of the pulverized coal is poor, causing frequent bridging of the pulverized coal bin, large fluctuations in the coal line, and affecting the stable operation of the coal gasification device. To solve this problem, the temperature of the high-pressure CO2 gas must be increased to 130°C. The common solution is to use steam, electricity or high-temperature condensate for heating, but it consumes additional energy and increases production costs. In the process of compressing the gas, part of the mechanical energy of the CO2 compressor is converted into thermal energy, and the gas temperature rises. It is necessary to set a water cooler at the outlet of each section to cool the high-temperature gas before entering the next section of compression. The heat of the high-temperature gas is not utilized, and there is heat waste. Utility Model Content

[0003] The purpose of the utility model is to provide a compressor waste heat recovery system to recycle the heat generated by the compressor compressing the gas, increase the temperature of the high-pressure CO2 gas, eliminate the adverse effects of the low temperature of the high-pressure CO2 gas on the stability of the gasification device, improve the operating stability of the gasification device, save energy and reduce production costs.

[0004] A compressor waste heat recovery system, characterized in that it comprises a steam turbine, a low-pressure cylinder, a high-pressure cylinder and a process gas pipeline connected by shafts, a first-stage impeller and a second-stage impeller are arranged in the low-pressure cylinder, and a third-stage impeller and a fourth-stage impeller are arranged in the high-pressure cylinder;

[0005] The process pipeline is connected from the CO2 desorption tower of the low-temperature methanol washing process, and then the inlet pressure regulating valve is set to the middle of the first inlet separator, and then connected to the first impeller of the low-pressure cylinder from the top of the first inlet separator, and connected to the shell side of the first outlet cooler from the outlet of the first impeller, and then enters the middle of the first outlet separator, and then connected from the top to the second impeller of the low-pressure cylinder, and then connected to the shell side of the high-pressure CO2 recuperator through the shell side inlet pipe, and then connected to the shell side of the second outlet cooler through the shell side outlet pipe, and then connected to the middle of the second outlet separator, and then connected to the third impeller of the high-pressure cylinder from the top, and then out from the third impeller The outlet is connected to the shell side of the three-stage outlet cooler, and then connected to the middle of the three-stage impeller outlet separator, and then connected to the four-stage impeller of the high-pressure cylinder from its top, and then connected to the tube side of the high-pressure CO2 reheater through the tube side inlet pipe, and then connected to the tube side of the tube side outlet pipe, and then divided into two routes, one route is set with a four-stage outlet vent valve and then emptied, and the other route is set with a high-pressure CO2 shut-off valve and then connected to the pipeline transported to the coal gasification device, and then divided into three routes, the first route is the pulverized coal conveying pipe, the second route is used to connect to the coal ash conveying pipe and the safety valve purge pipe after passing through the heater I, and the third route is connected to the quencher, the synthesis gas cooler and the fly ash filter backflush pipe through the heater II;

[0006] A tube bypass pipe of the high-pressure CO2 reheater is connected between the tube inlet pipe and the tube outlet pipe of the high-pressure CO2 reheater, and a temperature regulating valve is provided;

[0007] A gas thermometer is installed on the tube outlet pipe of the high-pressure CO2 recuperator, the gas thermometer is electrically connected to the temperature controller, and the temperature controller is electrically connected to the temperature regulating valve;

[0008] A pipeline provided with a low-pressure cylinder anti-surge valve is connected between the pipeline connected to the first-stage impeller of the low-pressure cylinder and the pipeline connected to the third-stage impeller of the high-pressure cylinder;

[0009] A pipeline with a high-pressure cylinder anti-surge valve is arranged between the pipeline connected to the second-stage impeller of the low-pressure cylinder and the pipeline connected to the fourth-stage impeller of the high-pressure cylinder;

[0010] A high-pressure N2 pipeline is connected before the pipeline branch to the coal gasification unit and a high-pressure N2 shut-off valve is installed.

[0011] Furthermore, the first-stage outlet cooler, the second-stage outlet cooler and the third-stage outlet cooler are all U-tube heat exchangers, with CO2 gas in the shell side and circulating cooling water in the tube side.

[0012] Furthermore, the high-pressure CO2 recuperator is a U-tube heat exchanger, the shell side contains high-temperature CO2 gas output by a two-stage impeller, and the tube side contains low-temperature CO2 gas output by a four-stage impeller.

[0013] The beneficial effects of the utility model are that the system recovers the waste heat of the high-temperature gas between compressor stages to increase the temperature of the high-pressure CO2 gas, thereby solving the problems of poor fluidity of pulverized coal, frequent bridging of pulverized coal bins and large fluctuations in the coal line caused by the low temperature of the high-pressure CO2 gas in the coal gasification device, greatly improving the operating stability of the coal gasification device, and reducing the heat load of the water cooler between the compressor stages and the steam consumption of the high-pressure CO2 heater. It has the characteristics of simple operation, strong practicality and high degree of automation, and is of great beneficial value to improving the energy utilization efficiency of the enterprise, saving energy and reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a pipeline connection diagram for a compressor waste heat recovery system.

[0015] Among them: 1-steam turbine, 2-low-pressure cylinder, 3-high-pressure cylinder, 4-first-stage inlet separator, 5-first-stage outlet cooler, 6-first-stage outlet separator, 7-second-stage outlet cooler, 8-second-stage outlet separator, 9-third-stage outlet cooler, 10-third-stage outlet separator, 11-heater I, 12-heater II, 13-high-pressure CO2 reheater, 14-gas thermometer, 15-temperature controller, 16-inlet pressure regulating valve, 17-low-pressure cylinder anti-surge valve, 18-high-pressure cylinder anti-surge valve, 19-fourth-stage outlet vent valve, 20-high-pressure CO2 shut-off valve, 21-high-pressure N2 shut-off valve, 22-temperature regulating valve, 23-shell side inlet pipe, 24-shell side outlet pipe, 25-tube side inlet pipe, 26-tube side outlet pipe, 27-bypass pipe DETAILED DESCRIPTION

[0016] Embodiment 1: A compressor waste heat recovery system, as shown in the attached Figure 1 As shown, it includes a steam turbine 1, a low-pressure cylinder 2, a high-pressure cylinder 3 and a process gas pipeline connected by shafts. The low-pressure cylinder 2 is provided with a first-stage impeller and a second-stage impeller, and the high-pressure cylinder 3 is provided with a third-stage impeller and a fourth-stage impeller.

[0017] The process pipeline is connected from the CO2 desorption tower of the low-temperature methanol washing process, and then the inlet pressure regulating valve 16 is set and connected to the middle of the first inlet separator 4, and then connected to the first impeller of the low-pressure cylinder 2 from the top of the first inlet separator 4, and connected to the shell side of the first outlet cooler 5 from the outlet of the first impeller, and then enters the middle of the first outlet separator 6, and then connected from its top to the second impeller of the low-pressure cylinder 2, and then connected to the shell side of the high-pressure CO2 recuperator 13 through the shell side inlet pipe 23, and then connected to the shell side of the second outlet cooler 7 through the shell side outlet pipe 24, and then connected to the middle of the second outlet separator 8, and then connected to the third impeller of the high-pressure cylinder 3 from its top, and then from the third impeller The outlet is connected to the shell side of the three-stage outlet cooler 9, then connected to the middle of the three-stage outlet separator 10, and then connected to the four-stage impeller of the high-pressure cylinder 3 from its top, and then connected to the tube side of the high-pressure CO2 recuperator 13 through the tube side inlet pipe 25, and then connected to the tube side outlet pipe 26, and then divided into two routes, one route is set with a four-stage outlet vent valve 19 and then emptied, and the other route is set with a high-pressure CO2 cut-off valve 20 and then connected to the pipeline transported to the coal gasification device, and then divided into three routes, the first route is the pulverized coal conveying pipe, the second route is connected to the coal ash conveying pipe and the safety valve purge pipe after passing through the heater I 11, and the third route is connected to the quencher, the synthesis gas cooler and the fly ash filter backflush pipe through the heater II 12. The tube side bypass pipe 27 of the high-pressure CO2 recuperator is connected between the tube side inlet pipe 25 and the tube side outlet pipe 26, and a temperature regulating valve 22 is set. A gas thermometer 14 is installed on the pipe outlet pipe 26, and the gas thermometer 14 is electrically connected to the temperature controller 15, and the temperature controller 15 is electrically connected to the temperature regulating valve 22. A pipeline with a low-pressure cylinder anti-surge valve 17 is set between the pipeline connected to the first-stage impeller of the low-pressure cylinder 2 and the pipeline connected to the third-stage impeller of the high-pressure cylinder 3. A pipeline with a high-pressure cylinder anti-surge valve 18 is set between the pipeline connected to the second-stage impeller of the low-pressure cylinder 2 and the pipeline connected to the fourth-stage impeller of the high-pressure cylinder 3. A high-pressure N2 pipeline is connected to the pipeline branch to the coal gasification device and a high-pressure N2 cut-off valve 21 is set.

[0018] The first stage outlet cooler 5, the second stage outlet cooler 7 and the third stage outlet cooler 9 are all U-shaped tube heat exchangers, with CO2 gas in the shell side and circulating cooling water in the tube side. The high-pressure CO2 recuperator 13 is a U-shaped tube heat exchanger, with high-temperature CO2 gas output by the second stage impeller in the shell side and low-temperature CO2 gas output by the fourth stage impeller in the tube side.

[0019] The low-pressure CO2 gas with a pressure of 0.11MPa and a temperature of 30°C in the CO2 desorption tower of the low-temperature methanol washing process is controlled to 0.07MPa by the inlet pressure regulating valve 16, and then enters the middle of the first-stage inlet separator 4, separates the liquid substances carried in the gas and flows out from the top, enters the first-stage impeller of the low-pressure cylinder 2 for compression, and the pressure rises to 0.42MPa and the temperature rises to 143°C, flows out from the first stage, enters the first-stage outlet cooler 5, and the shell side is cooled to 35°C by the circulating cooling water in the heat exchange tube, and then enters the middle of the first-stage outlet separator 6, separates the liquid substances in the gas and flows out from the top, enters the second-stage impeller of the low-pressure cylinder 2 for compression, and the pressure rises to 2.05MPa and the temperature rises to 190°C, flows out from the second-stage impeller, enters the shell side of the high-pressure CO2 recuperator 13, heats the tube side with 8.2MPa high-pressure CO2 from the fourth-stage impeller, and enters the second The shell side of the stage outlet cooler 7 is cooled to 35°C by the circulating cooling water in the heat exchange tube, enters the middle part of the second stage outlet separator 8, separates the liquid substances in the gas and flows out from the top, enters the three-stage impeller of the high-pressure cylinder 3 for compression, the pressure rises to 5.0MPa, the temperature rises to 115°C, flows out from the three-stage outlet pipe, enters the three-stage outlet cooler 9, the shell side is cooled to 35°C by the circulating cooling water in the heat exchange tube, enters the middle part of the three-stage outlet separator 10, separates the liquid substances in the gas and flows out from the top, enters the four-stage impeller of the high-pressure cylinder 3 for compression, the pressure rises to 8.2MPa, the temperature rises to 90°C, flows out from the four-stage outlet pipe, enters the high-pressure CO2 recuperator 13 pipe side, is heated by the 190°C high-temperature gas from the second-stage impeller of the low-pressure cylinder 2 in the shell side, the temperature rises to 130°C, and is sent to the coal gasification device after the pressure is controlled by the four-stage outlet vent valve 19 and the temperature is controlled by the temperature controller 15.

[0020] After the high-pressure CO2 gas with a pressure of 8.2MPa and a temperature of 130℃ is sent to the coal gasification unit, it is divided into three routes: the first route is reduced in pressure to 5.0MPa for conveying pulverized coal, the second route is reduced in pressure to 5.2MPa and heated to 225℃ by steam through heater Ⅰ11 for conveying coal ash and purging the safety valve, and the third route is reduced in pressure to 7.8MPa and heated to 225℃ by steam through heater II12 for back-blowing the quencher, synthesis gas cooler and fly ash filter.

[0021] The steps for commissioning a compressor waste heat recovery system of the utility model are as follows:

[0022] (1) Before starting the compressor, fully close the high-pressure CO2 shut-off valve 20, set the temperature controller 15 to the "MAN" (manual) position, enter the OP value as "100%, and fully open the temperature regulating valve 22 on the bypass pipe 27 of the high-pressure CO2 reheater 13; fully open the low-pressure cylinder anti-surge valve 17, the high-pressure cylinder anti-surge valve 18 and the four-stage outlet vent valve 19. Slightly open the inlet pressure regulating valve 16, introduce the CO2 gas from the CO2 desorption tower of the low-temperature methanol washing process into the compressor, and vent it at the four-stage outlet vent valve 19.

[0023] (2) Start the compressor according to the CO2 compressor operating procedures and increase the fourth stage outlet pressure to 8.2 MPa.

[0024] (3) Slowly close the temperature regulating valve 22 and gradually increase the temperature to 130°C.

[0025] (4) Slowly open the high-pressure CO2 shut-off valve 20 until it is fully open, and at the same time slowly close the high-pressure N2 shut-off valve 21 until it is fully closed. In addition, slowly close the four-stage outlet vent valve 19 on the principle of maintaining the high-pressure CO2 pressure stable, and switch the high-pressure N2 to high-pressure CO2.

[0026] (5) After the system operating conditions stabilize, the temperature controller 15 is set to "AUTO" (automatic) and the SP is set to 130°C, and the high-pressure CO2 temperature is automatically controlled by the DCS.

Claims

1. A compressor waste heat recovery system, characterized in that: It includes a steam turbine, a low-pressure cylinder, a high-pressure cylinder and a process gas pipeline connected by shafts, a first-stage impeller and a second-stage impeller are arranged in the low-pressure cylinder, and a third-stage impeller and a fourth-stage impeller are arranged in the high-pressure cylinder; The process pipeline is connected from the CO2 desorption tower of the low-temperature methanol washing process, and then the inlet pressure regulating valve is set to the middle of the first inlet separator, and then connected to the first impeller of the low-pressure cylinder from the top of the first inlet separator, and connected to the shell side of the first outlet cooler from the outlet of the first impeller, and then enters the middle of the first outlet separator, and then connected from the top to the second impeller of the low-pressure cylinder, and then connected to the shell side of the high-pressure CO2 recuperator through the shell side inlet pipe, and then connected to the shell side of the second outlet cooler through the shell side outlet pipe, and then connected to the middle of the second outlet separator, and then connected to the third impeller of the high-pressure cylinder from the top, and then out from the third impeller The outlet is connected to the shell side of the three-stage outlet cooler, and then connected to the middle of the three-stage impeller outlet separator, and then connected to the four-stage impeller of the high-pressure cylinder from its top, and then connected to the tube side of the high-pressure CO2 reheater through the tube side inlet pipe, and then connected to the tube side of the tube side outlet pipe, and then divided into two routes, one route is set with a four-stage outlet vent valve and then emptied, and the other route is set with a high-pressure CO2 shut-off valve and then connected to the pipeline transported to the coal gasification device, and then divided into three routes, the first route is the pulverized coal conveying pipe, the second route is connected to the coal ash conveying pipe and the safety valve purge pipe after passing through the heater I, and the third route is connected to the quencher, the synthesis gas cooler and the fly ash filter backflush pipe after passing through the heater II; A tube bypass pipe of the high-pressure CO2 reheater is connected between the tube inlet pipe and the tube outlet pipe of the high-pressure CO2 reheater, and a temperature regulating valve is provided; A gas thermometer is installed on the tube outlet pipe of the high-pressure CO2 recuperator, the gas thermometer is electrically connected to the temperature controller, and the temperature controller is electrically connected to the temperature regulating valve; A pipeline provided with a low-pressure cylinder anti-surge valve is connected between the pipeline connected to the first-stage impeller of the low-pressure cylinder and the pipeline connected to the third-stage impeller of the high-pressure cylinder; A pipeline with a high-pressure cylinder anti-surge valve is arranged between the pipeline connected to the second-stage impeller of the low-pressure cylinder and the pipeline connected to the fourth-stage impeller of the high-pressure cylinder; A high-pressure N2 pipeline is connected before the pipeline branch to the coal gasification unit and a high-pressure N2 shut-off valve is installed.

2. A compressor waste heat recovery system according to claim 1, characterized in that The first-stage outlet cooler, the second-stage outlet cooler and the third-stage outlet cooler are all U-tube heat exchangers, with CO2 gas in the shell side and circulating cooling water in the tube side.

3. A compressor waste heat recovery system according to claim 1, characterized in that The high-pressure CO2 recuperator is a U-tube heat exchanger, wherein the shell side carries high-temperature CO2 gas output by a two-stage impeller, and the tube side carries low-temperature CO2 gas output by a four-stage impeller.

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